Monitor technologies

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There’s more than one way to make a monitor but no matter what the technology, they all share one very important common feature: the pixel. Once you understand that all monitors have pixels, it’s easier to understand the different technologies that make up a modern monitor.

- Hey, look at me, I'm in a monitor! It's funny, we never really think about our monitors that much, but it is the primary device by which your computer provides output so we know what our computer's doing. I mean everybody's got a monitor, but how do they work? Well, the secret to monitors is understanding that this image is actually created by hundreds of thousands, millions possibly, of these little tiny elements called pixels. Now, if you want to see a pixel, well, I'm going to show you one right now. But in order to do that, we're going to have to zoom in. I mean way in. I mean you've got to zoom in like crazy here and I'm going to show you the world's largest pixel. So what I'm holding in front of me is a pixel or what we call a picture element. A picture element consists of three individual pieces that emit red, green, and blue light, so let's talk about this for a second. Each one of these individual elements is actually a liquid crystal display or LCD. The colors are just film put on top of them, so let's wipe the color away for a minute and now if we look at any one of these individual LCD elements, if we put electricity onto an element, it goes clear and light can go through it. If we take electricity away, it becomes completely opaque and light cannot go through it. So that works for all three of these. In fact, if we want to, we could even adjust the amount of light so they kind of dim or brighten and that allows us to have different colors of light. This is where the famous RGB values of light come from. So what I'd like to do now is let's go ahead and let's put our covers back on so we're back to our red, green, and blue. So, the first thing you need to be aware of with LCD is that this doesn't glow, right, the only thing that happens is LCD can either let light pass or block light. So all LCD monitors have to have some kind of backlighting to them. Now, on the first generation LCDs we used a cold cathode fluorescent lamp or CCFL, although in today's systems, good ole light emitting diodes or LEDs are used. So you always want to separate the imaging, which is LCD, from the backlight, which could be CCFL or LED on the vast majority of LCD panels today. Now, if I want to generate the color green, say, what I'm going to be doing is I'm going to make sure that there's absolutely no charge on the blue and that there's no charge on the red, so that's going to block light, and then I'm going to put a big charge on the green which will clear it and my backlight will come right through and it'll be nice and pretty and green. By putting different combinations of red, green, and blue values in, I can make just about any color in the rainbow that you might want. Now, the other thing that comes into play with these types of panels is that there's a lot of different types of LCD technologies out there. They have names like TN, which stands for, what is that, somebody write it down for me, there you go, that's a TN panel or IPS. These different panels have different benefits. For example, right now TN is very inexpensive and it has a pretty good speed to it, whereas IPS is very popular because it has a very wide range of view, which a lot of people really appreciate. Now, when we're talking about these panels, a few things come into play. One of the big things is resolution. Now, keep in mind that these pixels are fixed, so the mosaic of pixels that we have is going to have a number of pixels across by a number of pixels down. So we could see numbers like, oh, there's so many different resolutions and we'll cover that in another episode, but one might be 1,280 across by 1,024 down. Or we could have 1,920 by 1,080, for example. There's a lot of different resolutions out there. The other big thing that we worry about with our panels is the brightness. So when we talk about brightness, we use a value called nits. So a nit is a measure of light, and for panels these days we're looking anywhere from 200 to 500 nits for a really good LCD panel. The other big issue is response time. You got to keep in mind, especially when you have motion going on in your screen, the panel has to, in essence, be able to reset itself so that we have that persistence of vision which allows us human beings to detect motion. Now, back in the old days we used to use a term called refresh rate, and that's kind of passe these days. A response time is basically how long does it take for one of these pixels to go from all black to all white and back to black again, and it's a better measure. Today's better monitors will have response times from around as fast as one millisecond up to four milliseconds, which is absolutely fantastic. Okay, now that's all absolutely wonderful, but there's a couple of things you need to be careful about. For example, one of the things that you'll hear a lot is people will go, oh, I'm selling an LED monitor. No they're not, they're selling an LCD monitor that has an LED backlight. LCD is very much king when it comes to monitors these days. However, there are other technologies out there, and keep in mind we have things like smart devices now and we have also projectors, so we can watch our movies. So there are two other technologies I want to mention. The first one, let's look back at our RGB one more time. So imagine I've got an RGB where each one of these is like a light bulb, a red light bulb, a green light bulb, and a blue light bulb. That's what we call organic LED or OLED. OLED has some real benefits. First of all, you can make really thin monitors with it. In fact, that's why so many smart devices have OLED screens, mainly because it's so thin, it's absolutely incredible. Also, we haven't seen it yet really, I mean I've seen it, but I'm talking like not at my local electronics store where I could have flexible monitors. I just can't wait for that day I can roll my monitor up and put it in my back pocket and just go anywhere I want. Now there is one other technology I want to mention, and that is DLP. DLP is a fascinating technology that focuses on the idea of having, instead of individual pixels in the classic sense, imagine a grid of zillions of tiny, tiny, and I mean really tiny mirrors. And these mirrors are set up in a grid that defines the resolution. And what you end up doing is you take a light source and that light source, there's other ways to do it, this is one way to do DLP, you have a light source that is going through a color wheel that's spinning out RGB color, and so this light's turning on and off very quickly, and it's hitting this big grid of mirrors and it then reflects out and you make all the different colors. We don't see DLP on monitors very much although it is still quite popular with projectors. All right, so the big takeaway on this episode is that you have a good rough concept of the different types of technologies that are out there. I think the next step is I feel like ripping a monitor open. (upbeat music)

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4/26/2019

CompTIA A+ is the leading entry-level, vendor-neutral certification for IT professionals. CompTIA A+ (220-1001): Cert Prep is a comprehensive 10-part series designed to help you prepare and pass the A+ Core 1 (220-1001) exam. This course—the fifth installment in the series—helps you study for exam objectives related to display technologies such as monitors, graphics cards, and projectors. CompTIA expert Mike Meyers also explains how to set up multiple monitors and troubleshoot display problems.